The present invention relates to an apparatus for forming gobs supplied from a feeder into bottles of specified finished shape.
Heretofore known as such apparatus are so-called I.S. machines for forming bottles, as disclosed in U.S. Pat. No. 1,911,119. Because of their production efficiency and economy, I.S. machines are widely used in the bottle making industry. I.S. machines include sections each comprising a mold for forming a gob into an inverted parison, a mouth mold for forming the mouth of the bottle to a finish while forming the parison, a finishing mold for shaping the parison to a finished bottle in the normal proper position, inverting assembly supporting the mouth mold and turnable through 180 degrees in a vertical plane for transferring the inverted parison to the finishing mold in the proper position, etc. Gobs are supplied in a predetermined order from a feeder to the parison forming molds of the sections, in each of which the above-mentioned components operate in specified sequence to form glass bottles. The glass bottles molded in the sections are transferred one after another onto a common conveyor as aligned in a continuous row at substantially equal spacing.
Suitable molding processes in this case are the press blow process (PB process) which is chiefly used for forming wide-mouthed bottles and in which the parison is formed by pressing, followed by blow molding for finishing, and the blow blow process (BB process) which is used mainly for forming small-mouthed bottles and in which parison forming and finishing are both done by blowing. Since bottles made by the PB process are uniform in wall thickness and advantageous in strength and can be made lightweight, attempts have been made to mold bottles with small mouths also by the PB process.
When small-mouthed bottles are to be formed by the PB process, the parison must be held with its surface separated from the mold so that although the parison has been deprived of heat from its outer surface by contact with the mold, the parsion can be reheated with its own internal heat to render the glass material smoothly stretchable for uniform shaping by the finishing step. With conventional I.S. machines, however, the parison formed by a mold is merely released therefrom by opening the mold, that is, by removing the mold which cools the surface of the parison, and the parison is reheated as mentioned above. Thus the parison surface is reheated by the internal heat while being exposed to the atmosphere, which tends to remove heat from the parison surface. This leads to a reduced reheating efficiency, giving rise to the necessity for a prolonged period of reheating to assure satisfactory blow molding for finishing. The time available for reheating is the period of time after the parison forming mold has been opened until the parison is transferred from the parison forming station to the finishing station, and the period of time after the parison has reached the finishing station and before finishing is started. To obtain a sufficient reheating time, therefore, there is the need to prolong the time taken for the transfer of the parison from the forming station to the finishing station, or to delay the start of the finishing operation. In either case, the bottle forming machine must then be operated at a greatly reduced speed. This results in a marked reduction in operation efficiency. Since the parison is transferred with its shaped bottle mouth portion held by the transfer means, a prolonged transfer time will permit the bottle neck portion to markedly bend or stretch due to the gravity acting on the unsupported bottle body portion, consequently causing trouble to the finishing operation.
Further with conventional I.S. machines, the parison or bottle is taken out and transferred to the next step or to a conveyor by a simple takeout comprising a reciprocally pivotally movable arm and tongs attached to the forward end of the arm for supporting the workpiece in suspension, such that the arm is turned through 180 degrees to move the tongs for the transfer of the workpiece. However, because the takeout is adapted to carry the workpiece in suspension with its bottle mouth portion only held by the tongs, an uncooled workpiece, especially a fully reheated and soft parison, is likely to stretch, bend or otherwise deform under gravity or due to inertia, whereas the semicircular path of transfer of the workpiece along which it is substantially moved is about 1.5 times as long as the required distance of travel, and the workpiece must be raised a distance which is one half the required distance of travel. As a result, the parison is liable to deform to a great extent. While being handle automatically, for example, for filling, bottles, if deformed, will contact one another more frequently than usually or strike the filling head, and are therefore susceptible to damage or break.